Quantum sensing of light or the detection of single photons is well known and is achievable in many devices. Photons are single light elements, and detection of the energy of single photons can be desirable in several settings. Phototubes, photomultipliers, avalanche solid state photodiodes, and HgCdTe detectors are all quantum detectors that can, broadly, be classified as photon-counting and photon-number-resolving detectors. Such detectors can in some instances be set-up as heterodyne detectors (which detect interference in laser light moving between a local source and returning laser light). Because the detection in such devices is done through electric charge, without multiplexing, these detectors are color blind. For example, in a HgCdTe detector, detection occurs when an infrared photon of sufficient energy kicks an electron from the valence band to the conduction band. Such an electron is collected by a suitable external readout circuit and transformed into an electric signal. Once the electron is in the valence band, the energy information of the electron is lost because the electron energy is thermalized by collisions in the valence band.
A bolometer is another energy detection device. In contrast to the devices described above, in a bolometer, light heats up a tiny piece of material. The bolometer then operates like a calorimeter, measuring power. The temperature change of the bolometer is measured and transformed into an electric signal. Known bolometer devices, however, cannot resolve energies of a single photon to determine photon color because the sensing element or device heat capacity or size obscures finer energy variations.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.